Dialup access can be either analog or digital. A conventional analog modem dials into the service provider over the public telephone network, achieving speeds up to 56 Kbps. A dialup digital connection using Integrated Services Digital Network (ISDN) achieves a speed of 128 Kbps, better transmission quality, and supports a voice call or fax transmission alongside Internet access. In both analog and digital dialup connections, the connection is established and disconnected (circuit-switched) by the user for each session.